Kaufman, Peter A.

Purpose To assess whether trastuzumab (H) with radiotherapy (RT) increases adverse events (AEs) after breast-conserving surgery or mastectomy. Patients and Methods Patients with early-stage resected human epidermal growth factor receptor 2 (HER-2) –positive breast cancer (BC) were randomly assigned to doxorubicin (A) and cyclophosphamide (C), followed by weekly paclitaxel (T; AC-T-H or AC-TH-H). RT criteria (with or without nodal RT) were postlumpectomy breast or (optional) postmastectomy chest wall. RT of internal mammary nodes was prohibited. RT commenced within 5 weeks after T, concurrently with H. Analysis included 1,503 irradiated patients for RT-associated AEs across treatment arms. Rates of cardiac events (CEs) with and without RT were compared within arms. Results No significant differences among arms were found in incidence of acute skin reaction, pneumonitis, dyspnea, cough, dysphagia, or neutropenia. A significant difference occurred in incidence of leukopenia, with higher rates for AC-T-H versus AC-T (odds ratio = 1.89; 95% CI, 1.25 to 2.88). At a median follow-up of 3.7 years (range, 0 to 6.5 years), RT with H did not increase relative frequency of CEs regardless of treatment side. The cumulative incidence of CEs with AC-T-H was 2.7% with or without RT. With AC-TH-H, the cumulative incidence was 1.7% v 5.9% with or without RT, respectively. Conclusion Concurrent adjuvant RT and H for early-stage BC was not associated with increased acute AEs. Further follow-up is required to assess late AEs.

Purpose To assess cardiac safety and potential cardiac risk factors associated with trastuzumab in the NCCTG N9831 Intergroup adjuvant breast cancer trial. Patients and Methods Patients with HER2-positive operable breast cancer were randomly assigned to doxorubicin plus cyclophosphamide (AC) followed by either weekly paclitaxel (arm A); paclitaxel then trastuzumab (arm B); or paclitaxel plus trastuzumab then trastuzumab alone (arm C). Left ventricular ejection fraction (LVEF) was evaluated at registration and 3, 6, 9, and 18 to 21 months. Results Of 2,992 patients completing AC, 5.0% had LVEF decreases disallowing trastuzumab (decrease below normal: 2.4%, decrease > 15%: 2.6%). There were 1,944 patients with satisfactory or no LVEF evaluation who proceeded to post-AC therapy. Cardiac events (congestive heart failure [CHF] or cardiac death [CD]): arm A, n = 3 (2 CHF, 1 CD); arm B, n = 19 (18 CHF, 1 CD); arm C, n = 19 (all CHF); 3-year cumulative incidence: 0.3%, 2.8%, and 3.3%, respectively. Cardiac function improved in most CHF cases following trastuzumab discontinuation and cardiac medication. Factors associated with increased risk of a cardiac event in arms B and C: older age (P < .003), prior/current antihypertensive agents (P = .005), and lower registration LVEF (P = .033). Incidence of asymptomatic LVEF decreases requiring holding trastuzumab was 8% to 10%; LVEF recovered and trastuzumab was restarted in approximately 50%. Conclusion The cumulative incidence of post-AC cardiac events at 3 years was higher in the trastuzumab-containing arms versus the control arm, but by less than 4%. Older age, lower registration LVEF, and antihypertensive medications are associated with increased risk of cardiac dysfunction in patients receiving trastuzumab following AC.

Purpose To evaluate concordance between local and central laboratory HER2 testing results in patients from the North Central Cancer Treatment Group (NCCTG) N9831 adjuvant trial of trastuzumab. Patients and Methods NCCTG N9831 is a randomized, phase III clinical trial comparing three drug regimens: doxorubicin/cyclophosphamide followed by paclitaxel with trastuzumab added concurrently, sequentially, or not at all as adjuvant therapy for women with HER2-positive resected breast cancer. Originally, patients were eligible if their tumors were HER2 positive by either local laboratory immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH). A protocol modification in 2002 made central laboratory testing mandatory, with additional testing of discordant cases conducted by a reference laboratory. Concordance between local and central laboratory, and level of agreement between central and reference laboratory HER2 findings in discordant cases were examined. Results HER2 positivity was confirmed in 85.8% of 2,535 patients registered since March 2002. When local and central evaluation used the same methodology, concordance was 88.1% for FISH and 81.6% for a diagnostic test for presence of the HER2 protein. Among discordant cases examined at the reference laboratory, there was 94.3% agreement for IHC (0, 1+, 2+) and 95.2% agreement for FISH (not gene amplified). Conclusion There was a high degree of discordance between local and central testing for IHC and FISH, but a high degree of agreement between central and reference laboratories. These findings support the importance of using high-volume, experienced laboratories for HER2 testing to improve the process of selecting patients likely to benefit from trastuzumab therapy.

Purpose To evaluate changes in left ventricular ejection fraction (LVEF) after four cycles of adjuvant doxorubicin plus cyclophosphamide (AC) in women with human epidermal growth factor receptor 2–positive (node-positive or node-negative) breast cancer enrolled onto the North Central Cancer Treatment Group N9831 Intergroup Adjuvant Trial. Patients and Methods Patients were randomly assigned to receive standard doxorubicin (60 mg/m2) plus cyclophosphamide (600 mg/m2) every 3 weeks for four cycles followed by (1) weekly paclitaxel for 12 weeks; (2) weekly paclitaxel for 12 weeks, then weekly trastuzumab for 52 weeks; or (3) weekly paclitaxel plus trastuzumab for 12 weeks, then weekly trastuzumab for 40 weeks. LVEF was monitored before and after AC. Results Of the 1,576 eligible patients who completed AC, 1,458 had pre- and post-AC LVEF measurements taken using the same methodology (multiple-gated acquisition in 1,153 patients and echocardiogram in 305 patients). Among these 1,458 patients, 745 (51.1%) had ≤ 15% decrease in LVEF and LVEF that remained at or above the radiologic lower limit of normal (LLN); 42 patients (2.9%) had ≤ 15% decrease in LVEF and LVEF that decreased to or below the LLN; and 37 patients (2.5%) had an LVEF decrease of more than 15%. There was grade 2 LVEF toxicity in 96 (6.6%) of the 1,458 patients. Conclusion Standard AC chemotherapy is associated with frequent decreases in LVEF, which are noted when measured 3 weeks after completion of the fourth cycle. Patients are being observed to determine the long-term significance of this and the potential impact on subsequent treatment options.